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Old 10th Sep 2019, 10:11 am   #1
electronicskip
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Default Marine Electronic Laboratories Type RT50 Transceiver

Ive been trying to find information on this Marine Radio I picked up last weekend but with little success.

The internet has very little information on it other than its a Marine band Transceiver.

Does anyone have any experience of this unit ?
Thanks in advance.
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Old 12th Sep 2019, 9:59 am   #2
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

No one has commented so far.
This looks like it will be FM at around 156MHz with 25kHz synthesised channels.
Not really useful for 2m amateur band conversion these days though back in the 1980's that might have made sense.
It is what it is or it's good for parts perhaps?
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Old 12th Sep 2019, 6:19 pm   #3
electronicskip
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

Seems a shame to break it for parts as ive never seen another and it powers up just fine, but im open to ideas as I only paid 4 for it.
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Old 12th Sep 2019, 10:53 pm   #4
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

I can't say what I would do with it...
I'm just too far from the sea to clip the TX PTT wire and say it's only an RX that gets turned on now and again by accident.
Or do you own a boat? It might be too old to use even then.
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Old 14th Sep 2019, 1:06 pm   #5
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

Hi

I have the RT100. I bought it back in the early '90s for pennies at a rally. The intention was to put it on a few 2m simplex frequencies. I never did. It has sat in the loft since.
Seeing this thread made me get it back out. It still works OK on TX &RX.

Does anyone know any history behind this brand?
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Old 14th Sep 2019, 5:15 pm   #6
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

Radio Museum gives
"Electronic Laboratories Ltd; Fleets Lane, Poole, Dorset BH15 36W, England
Brand: Seafarer"

They made all types of electronic marine equipment, echo sounders speed logs, radios, RDF equipment.

I believe the early marine VHF band was 50kHz channel spacing, it was then changed into 25kHz spacing to accommodate all the international channels. So I don't think it would be advisable to use either the RT50 or RT100 transceivers today.

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Old 14th Sep 2019, 11:07 pm   #7
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

That RT100 is a gem if only for the channel switch!
There was some lovely Marine band gear about in the '70s.

I used to have one RX - it was the NR56 I think. They could be for Marine or for 2m Amateur coverage. Both had 11x Crystals and the 12th position tunable with VFO AFIK.
Not sure which I had - maybe I frigged it from one to the other and back?
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Old 15th Sep 2019, 5:51 pm   #8
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

Quote:
Originally Posted by GSBX1220 View Post
Hi

I have the RT100. I bought it back in the early '90s for pennies at a rally. The intention was to put it on a few 2m simplex frequencies. I never did. It has sat in the loft since.
Seeing this thread made me get it back out. It still works OK on TX &RX.

Does anyone know any history behind this brand?
Lovely looking rig.
Reminds me of a 70s american cb.
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Old 15th Sep 2019, 6:32 pm   #9
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

there were - probably are - marine transceiver brands that also were applied to CBs, Midland was one and they were rather good looking
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Old 16th Sep 2019, 4:20 pm   #10
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

Yes you're correct and also Cobra produced marine rigs too, another top quality cb manufacturer.
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Old 18th Sep 2019, 7:58 am   #11
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

Hi

Some internal shots of the RT100. Thought it may be of some interest.

The green marks on the RX crystals are where they were in contact with the now rotting retaining foam pad on the crystal door.
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Old 18th Sep 2019, 8:48 am   #12
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

I recognise those boards. I have some of them somewhere.
I don't remember the crystals though so maybe it was later and synthesised?
For sure I recognise that PA board.
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Old 29th Sep 2019, 10:00 pm   #13
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

I think this radio would have been sold with some of the channels being the users choice.

The channel numbers are metal stickers and some are silver with black letttering and some are gold. The colour difference is what leads me to think these sets were sold with some standard channels, and some chosen by the end user.
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Old 5th Oct 2019, 9:10 am   #14
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

I have the circuit here, for the RT50 Mini-Seavoice, which is a UK brand.
Appears to use a synth with a couple of Plessey chips. Only crystal I can see is
20.945 MHz. The tens and units switches suggest full band coverage.
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Old 5th Oct 2019, 9:52 am   #15
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

20.945 mixes with 21.4MHz to give a 455kHz IF, so that is a dead give away for the IF structure... 21.4MHz then 455kHz.

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Old 5th Oct 2019, 10:13 am   #16
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

Quite right.

It's a fair bet that there will also be a 6.4MHz or 12.8MHz for synthesiser reference.
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Old 6th Oct 2019, 8:41 pm   #17
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

Other crystal is 10MHz. quite a lot of CMOS chips in the synth, e.g. MC145222, and
the SP8695 (16 dil) and SP8794 (8 dil) might be a prescaler. Design dated 1979.
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Old 9th Oct 2019, 5:09 pm   #18
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Default Re: Marine Electronic Laboratories Type RT50 Transceiver

I will open mine up and have a look to see what its running crystal wise at the moment.
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